Problem: Simplify the expression. $(-6n^{2}-6n)(-7n^{2}-7n)$
Answer: First use the distributive property. $ - 6 n^2 (-7 n^2) - 6 n^2 (-7 n) - 6 n (-7 n^2) - 6 n (-7 n) $ Simplify. $ 42n^{4} + 42n^{3} + 42n^{3} + 42n^{2} $ $42n^{4}+84n^{3}+42n^{2}$ Identify like terms. $ { 42n^{4}} {+ 42n^{3}} {+ 42n^{3}} {+ 42n^{2}} $ Add the coefficients. $ { 42n^{4}} {+ 84n^{3}} {+ 42n^{2}} $